Since their introduction in the early 1980's, microchannel heat sinks have shown much potential for high heat-flux cooling applications and have been used in the industry. However, existing microchannels include conventional parallel channel arrangements which are not optimally suited for cooling heat producing devices which have spatially-varying heat loads. Such heat producing devices have areas which produce more heat per unit area than others. These hotter areas are hereby designated as “hot spots” whereas the areas of the heat source which do not produce as much heat are hereby termed, “warm spots”. In the simplest case, a hot spot is an area of a heat source, for example a microprocessor, which has a substantially higher heat flux than the other areas of the heat source. In addition, a substantially varying heat flux across the surface of the heat source can induce temperature differences along the heat source surface, thereby forming multiple hot spots.
FIG. 1A illustrates a perspective view of a heat source 99 having multiple hot spots therein. As shown in FIG. 1A, although the hot spots have a higher heat flux than other areas in the heat source, a peripheral area proximal to the hot spot also has a higher temperature relative to the non-hot spot areas, due to the propagation of heat through the heat source material. Therefore, the area shown within the dashed lines in FIG. 1A that is peripheral to the hot spots are higher in temperature than the areas outside of the dashed lines. Therefore, the hot spot area as well as the immediate surrounding area is defined as the hot spot and is called an interface hot spot region.
Alternatively, the heat source 99 does not have any hot spots, as shown in FIG. 1B. FIG. 1B illustrates a perspective view of a heat source 99 having no hot spots therein along with an aligned graph which represents the temperature variation as a function of distance in the X and Y directions. Although the heat source 99 in FIG. 1B does not have any hot spots, the physics of heat propagation in materials dictates that the middle of the heat source 99 will have a higher heat flux than the surrounding areas and edges of the heat source 99. This is shown in the graph in FIG. 1B. Prior art heat exchangers only focus on cooling the heat source and thereby do not focus on the aspects of hot spot cooling or overall temperature uniformity.
What is needed is a fluidic cooling loop system with a heat exchanger utilizing various design controls and cooling methods to achieve temperature uniformity in the heat source. What is also needed is a fluidic cooling loop system with a heat exchanger utilizing various design and control methods to effectively cool hot spots in a heat source.